Circuit interrupter



May 5, 1970 R.' H. FLICK ET Al- -CIRCUIT INTERRUPTER 2 Sheets-Sheet l Filed July l2, 1967 May 5, 1970 R, H, ET AL CIRCUIT INTERRUPTER Filed July l2. 1967 lt?. Sheets-Sheet 2 Mawr,...

WITNESSES INVENTORS Rober? H. Fick and James P. Esworh ATTORNEY United States Patent O 3,510,817 CIRCUIT INTERRUPTER Robert H. Flick and `lames P. Ellsworth, Beaver, Pa.,

assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed July 12, 1967, Ser. No. 652,865 Int. 'CL H01h 85/00, 85 02 U.S. Cl. 337-6 6 Claims ABSTRACT F THE DISCLOSURE BRIEF SUMMARY OF THE INVENTION An improved circuit interrupter comprises a circuitV breaker and a fuse unit. The circuit breaker comprises an insulating housing and a circuitbreaker mechanism supported in the insulating housing. The circuit-breaker mechanism comprises a pair of contacts and an operating handle extending from the front of the housing to permit manual operation of the contacts. The circuit-breaker mechanism comprises a latched releasable member releasable to elfect automatic opening of the contacts, and current responsive trip means in electrical series with the contacts. Upon the occurrence of an overload below a predetermined value the trip means operates automatically in response to the overload to effect release of the releasable member. The fuse unit comprises an insulating housing. A fuse structure, comprising an insulating fuse holder and a fuse, is supported on the fuse unit housing. The fuse structure is removable through opening means at the front of the fuse unit housing. The circuit breaker and fuse unit are physically connected together, and the fuse structure is connected in electrical series with the trip means and contacts of the circuit breaker. Upon the occurrence a severe overload current above a predetermined Value the fuse blows to interrupt the current and to limit the current that will pass through the -circuit breaker. The combination comprises interlocking means between the fuse unit and the circuit breaker operating automatically when the fuse structure is removed to elfect release of the releasable member to trip the breaker and to maintain the breaker in the tripped condition while the fuse structure is removed.

OBJECTS OF THE INVENTION An object of this invention is to provide an improved circuit interrupter comprising a circuit breaker and a fuse unit attached to the circuit breaker with interlocking means operating automatically to trip the circuit breaker when the fuse structure is removed from the fuse unit and for maintaining the circuit breaker in a tripped condition while the fuse structure is removed.

Another object of this invention is to provide an improved circuit interrupter comprising a circuit breaker and a separate fuse unit attached to the circuit breaker which fuse unit interrupts a severe overload letting through enough current to magnetically trip the breaker, but operating fast enough to interrupt the overload be- 3,510,817 Patented May 5, 1970 ICC fore the current reaches a valve that would cause damage to the breaker parts.

Another object of this invention is to provide an improved circuit interrupter comprising a circuit breaker and a separate fuse unit attached to the circuit breaker in a side-by-side relationship.

Another object of this invention is to provide an improved circuit interrupter comprising a circuit breaker and a separate fuse unit attached to the circuit breaker in an end-to-end relationship.

Another object of this invention is to provide an improved circuit interrupter comprising a standard moldedcase front-operated type of circuit breaker and a molded case type fuse unit attached to the circuit breaker, which fuse unit comprises a fuse structure removable from the front of the circuit interrupter, and which combination comprises interlocking means for tripping the circuit breaker when the fuse structure is removed and for maintaining the circuit breaker in a tripped condition while the fuse structure is removed.

For a better understanding of the nature and objects of the invention, reference may be had to the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. l is a plan view of a circuit interrupter constructed in accordance with principles of this invention;

FIG. 2 is an end view of the circuit interrupter of FIG. l looking in the direction of the II-II arrows of FIG. 1;

FIG. 3 is a sectional view III of FIG. 1;

FIG. 4 is a sectional view taken along the line 1V- IV of FIG. 1;

FIG. 5 is a plan View of a circuit interrupter illustrating another embodiment of this invention;

FIG. 6 is an end view looking in the direction of the VI-VI arrows of FIG. 5; and

FIG. 7 is a sectional view taken generally along the line VII-VII of FIG. 5.

Referring to the drawings, there is shown, in FIGS. 1 and 2, a circuit interrupter 3 comprising a circuit breaker 5 and a fuse unit 7.

The circuit breaker 5 is a standard ty-pe of moldedcase circuit breaker comprising an insulating housing 9 and a circuit-breaker mechanism 11 (FIG. 4) supported within the housing 9. The circuit breaker 5 is of the type disclosed, for example, in the patent to F. L. Gelzheiser et al., Pat. No. 3,178,535, issued Apr. 13, 1965. As can be seen in FIGS. l and 2, the housing 9 comprises an insulating base 13 having an open-sided cavity (FIG.- 4) therein and an insulating cover 15 (FIGS. 1 and 2) secured to the base 13 by means of three rivets 17 (FIG. 4). The housing 9 is provided with an opening 19 in the front thereof, and a handle 21 extends from the opening to permit manual operation of the breaker in the manner to be hereinafter described.

The circuit breaker mechanism 11 tionary contact 23, a movable contact mechanism 27, a trip device 29 taken along the line III- comprises a sta- 25, an operating and an arc extinguisher The stationary contact 23 is fixed to the inner end of a conductor 33 that is connecteed to a plug-in or clip-on type terminal 35 supported in the housing 9 at the back part of the line end of the housing. The housing 9 is provided with an opening at the back line end thereof for receiving a conducting stab that will extend into the housing to engage the clip-on type connector 35 to connect the circuit breaker in an electric circuit when the breaker is mounted on a stab at a panelboard installation.

The movable contact 25 is secured to the free end of a U-shaped switch arm 37 of conducting material. The opposite legs of the switch arm 37 are supported in recesses in an insul-ating operating lever 39 that is pivotally -supported by trunnions 41, molded integral with the operating lever 39, that are mounted in openings in the housing members 13, 15. The insulatitng handle 21 is formed integral with the operating lever 39. An overcenter spring 43 is connected under tension between the bight portion of the switch arm 37 and a releasable cradle member 45 that is pivoted on a pin 47 supported on the housing members 13, 15. The free end 49 of the pivoted releasable member 45 is latched on la ledge portion of a latch member 51 that is part of the trip device 29.

The switch arm 37 is operated manually to open and close the contacts by operation of the operating lever 39. Clockwise movement of the handle 21 from the ON to the OFF position carries to pivoted ends of the legs of the switch arm 37 across to the left of the line of action of the overcenter spring 43 which then biases the switch arm 37 to the open position and causes movement of the switch arm 37 to the open position with a snap action. The contacts are manually closed by reverse movement of the operating lever 39 from the OFF to the ON position, which movement moves the upper pivoted ends of the legs of the switch arm 37 across to the right of the line of action of the spring 43 which then acts to move the switch arm 37 with a snap action to the closed position seen in FIG. 4.

The switch arm 37 is electrically connected to a bimetal member 55 by means of a flexible conductor 57. The upper end of the bimetal 55 is xedly secured to a terminal conductor 59 that is suitably supported in the housing 9 and that extends out to an open cavity at one end of the housing 9. A terminal screw 61 extends through an opening in an insulated connecting conductor 63 and through an opening in the external end of the conductor 59 to connect the conductor 63 with the terminal conductor 59.

The latch member 51 is pivotally supported, intermediate the ends thereof, on knife edge pivots 65 (only one of which is seen in FIG. 4) on the housing parts 13 and 15. A spring 67 biases the latch member 51 clockwise about the pivot 65 to the latching position shown in FIG. 4.

A trip device 29 comprises the bimetal 55, the latch member 51, and a U-shaped magnetic yoke 69 that is xed at the lower free end of the bimetal 55. The conductor 57 is looped around the magnet yoke 69 and connected to the lower free end of the bimetal 55. The latch member 51 lcomprises an armature portion 71 of magnetic material. Upon the occurrence of -a low persistent overload current below a predetermined value, the bimetal 55 is heated and bends toward the right. As can be seen in FIG. 4, the latch member 51 is bent-over to provide a short leg 73 on the opposite side of the bimetal 55. An insulating Ibutton 75 is secured to the leg 73 of the latch 51. When the bimetal 55 fiexes to the right, the yoke 69 engages the insulating button 75 and rotates the latch member 51 in a counterclockwise direction yabout the pivot 65 to release the releasable member 45. Upon release of the ON and OFF positions to provide a visual indicaable member 45 in a clockwise direction about the pivot 47 moving the line of force of the spring 43 to the right whereupon the spring 43 acts to move the switch arm 37 to the open position with a snap action. Movement of the releasable member 45 and switch arm 37 is limited by an insulating projection 79 that is formed integral with the housing part 13.

On the occurrence of an automatic tripping operation, the operating lever 39 is moved to a position intermediate the ON and OFF position, to provide a visual indication that the circuit breaker has tripped, in a manner well known in the art.

The releasable member 45 is reset and relatched follow. ing an automatic opening operation by movement of the handle 21 clockwise to the full OFF position, during which movement a lower leg portion 81 of the operating lever 39 engages a pin 83 on the releasable member 45 to move the releasable member 45 counterclockwise about the pivot 47 to the latched position, whereupon the spring 67 biases the latch member 51 counterclockwise to relatch the free end 49 of the releasable member 45 in a manner well known in the art. Thereafter, the circuit breaker can be operated in the same manner hereinbefore described.

When an overload current above the predetermined value such, for example, as ten times the normal rated current occurs, the electromagnetic trip means is energized to instantaneously trip the breaker. During this operation, the magnetic members 69, 71 are energized suiciently by the current ow to attract the magnetic member 71 toward the magnetic yoke 69 instantaneously to release the releasable member 45 whereupon the circuit breaker is tripped in the same manner hereinbefore described. After an electromagnetic tripping operation the circuit breaker is reset and relatched in the same manner as was hereinbefore described.

When the contacts 25, 23 open, an arc is extinguished in the arc extinguishing structure 31, and the arc gases are vented out through a vent passage 85 at one end of the circuit breaker under the terminal screw 61. The vent passage 85 is formed during the molding of the insulating housing part 13.

The fuse unit 7 comprises an insulating housing 87 having the same external dimensions as the insulating housing 9 of the circuit breaker 5. The insulating housing 87 cornprises two parts 89 and 91 having a cavity formed therebetween, which parts are secured together and secured to the insulating housing of the circuit breaker by means of the rivets 17. If desired, the insulating housing parts 13, 15 of the breaker can be secured together as a unit and the insulating housing parts 91, 89 of the fuse unit can be secured together as a unit; and the circuit breaker 5 and fuse unit 7 can be secured together by suitable securing means. If desired, the same rivets 17 can be used to secure all of the housing parts 13, 15, 87, 89 together as a unit.

The insulating housing 87 of the fuse unit 7 is provided with an opening 93 at the front thereof, and a fuse struc- `ture 95 is removably mounted in the housing 87 through the opening 93. The fuse structure 95 comprises a molded insulating handle structure 97 and a fuse 99. The fuse 99 comprises a main body fuse part 101, and fuse terminals 103, at opposite ends of the main body part 101. A resilient terminal 107 is mounted on the insulating housing 97 to make contact with the upper fuse terminal 103. A U-shape clip-terminal 109 is mounted in the insulating housing 87 to make contact with the lower fuse terminal 105. The fuse 99 is removably mounted on the fuse holder 97 with the fuse terminal 103 removably connected to the terminal 107. The insulating housing 87 is provided 'with a similar passage 85 that served as a vent passage for the circuit breaker 5. The insulated conductor 63 (FIGS. 1 4) extends from the terminal 59' of the circuit breaker 5 across to the fuse unit 5 and into the vent passage area 85 of the housing 87 of the fuse unit 5 where the conductor 63 is connected to a depending conducting part 113 depending from the terminal clip 109. A terminal conductor 115 is supported in the housing 87 for connection to the resilient terminal 107, and the conductor 115 extends to an outer cavity portion of the housing 87 for receiving a connecting screw 117 that can be used to removably connect a conductor to the fuse unit at the installation. Referring to FIGS. 14, Iwhen the circuit interrupter 3 is plugged onto a stab at a panelboard installation, a circuit extends from the stab to the clip-on type terminal 35, through the conductor 33, contacts 23, 25, switch arrn 37, flexible conductor 57, bimetal 55, terminal 59, conductor 63, terminal 109, the fuse 99, terminal 107, conductor 115, to a conducting line that would be connected to the conductor 115 by means of the screw 117 at the installation.

Upon the occurrence of a severe short circuit current above a predetermined value, the fuse 99 blows to interrupt the short circuit and limit the amount of current that will pass through the circuit breaker 5. Although enough current passes through the breaker to magnetically trip the breaker when the fuse blows, the fuse blows fast enough to interrupt the overload before the current reaches a value that would cause damage to the breaker parts. The fuse structure 95 can be removed by pulling on the handle 97 whereupon the terminal 105 is released from the clip-terminal 109 and whereupon the terminal 107 is released from the terminal 115. The blown fuse 99 is then pulled from the holder 97, and replaced by a good fuse that is merely forced into position in the holder 97 in contact with the resilient terminal 107. Thereafter, the fuse structure 95 is moved into the mounted position through the opening 93 to automatically engage the terminals 109, 115 as is seen in FIG. 3. Suitable keying means is provided between the fuse holder 97 and the housing 87 to provide that the terminal 107 Iwill be positioned to engage the terminal 115 when the fuse structure 95 is moved into the mounted position.

Safety means is provided for tripping the circuit breaker when the fuse structure 95 is removed from the circuit interrupter and for preventing a resetting oper-ation of the circuit breaker 5 Iwhile the fuse structure 95 is removed. Referring to FIG. 3, an insulating interlocking member 125 is pivotally supported in the housing 87 by means of -a pivot pin 127. The interlocking member 125 is provided with an extension 129 that is engaged by the lower end of the fuse terminal 105 when the fuse structure 95 is in the mounted position seen in FIG. 3. The interlocking member 125 is provided with a bent-over extension 131 (FIGS. 3 and 4) that extends through an opening (not shown) in one side wall of the fuse unit housing 87 and through an opening 135 (FIG. 4) in one side wall of the circuit breaker housing 9. A spring member 137 (FIG. 3) is supported between part of the nterlocking member 125 and a ledge portion 139 molded integral with the housing part 89 to bias the interlocking member 125 in a clockwise (FIG. 3) direction about the pivot 127. When the fuse structure 95 is removed, the terminal 105 (FIG. 3) moves away from the extension 129 releasing the interlocking member 125 'whereupon the spring 137 biases the interlocking member 125 clockwise (FIG. 3) whereupon the extension 131 engages the latch member 51 (FIG. 4) to move the latch member 51 counterclockwise (FIG. 4) to the unlatching position. The spring 43 then operates to move the releasable member 45 to the tripped position to trip the breaker if the fuse structure 95 is removed when the contacts are closed and to prevent a closing operation of the breaker if the fuse structure 95 is removed when the contacts are open. When the fuse structure 95 is removed 'with the breaker contacts closed the breaker will be tripped open before the terminals 105, 107 separate from the terminals 109, 115 respectively to thereby prevent arcing between the terminals 105, 107 and the terminals 109, 115 respectively. While the fuse structure 95 is removed, the latch member 51 (FIG. 4) is maintained in the unlatching position to prevent a resetting operation of the circuit breaker 5 to thereby prevent an operation that would close the contacts 23, 25 of the circuit breaker 5. When the fuse structure 95 is replaced, the terminal 105 engages the extension 129 of the interlocking member 125 to bias the interlocking member 125 back to the inoperative position seen in FIG. 3 to permit a resetting and relatching operation of the circuit breaker 5.

Another embodiment of the invention is disclosed in FIGS. 5-7. Referring to FIGS. 5-7, a circuit interrupter 155 comprises a circuit breaker 157 and a fuse unit 159'.

The circuit breaker 157 is like the circuit breaker 5 disclosed in FIGS. 1, 2 and 4, except that: the breaker opening 135 (FIG. 4) is not provided in the circuit breaker 157 and a different opening 160 is provided at the end of the housing of the circuit breaker 157 to receive Va diterent interlocking member 163, and the housing of the circuit breaker 157 is provided with a shoulder 165 and a cavity at the opening 160 for receiving a spring 167 that engages the shoulder 165 and a projection on the interlocking member 163 to bias the interlocking member 163 to the right as seen in FIG. 7. Since the circuit breaker 157 is otherwise the same as the circuit breaker 5 hereinbefore described, applicants have omitted the use of reference characters from FIGS. 5-7 for the purpose of clarity.

The fuse unit 159 comprises an insulating housing 161 comprising a molded insulating part 171 and a molded insulated part 173 secured together by means of a pair of rivets 175. A terminal conductor 1177, having a U- shaped clip type terminal 179 secured to the inner side thereof, extends to a cavity at the end of the housing 161 for receiving a terminal screw 181 that will be used at the installation to electrically connect a conducting wire to the terminal 177.

Another terminal conductor 183, which is supported at the other end of the housing 161, extends out through an opening at the other end. The terminal 183 is rigidly fixed in the housing 161 and is provided with an opening in the external end thereof for receiving the terminal screw 61 of the circuit breaker 157, which terminal screw 61 is used to connect the terminal 183 with the terminal 59 of the circuit breaker 157. A fuse structure 95', identical to the fuse structure 95 described with reference to FIG. 3, is mounted in an opening in the front of the housing 161 and connected to the terminals 183, 179 in the same manner as the fuse 95 in FIG. 3 was mounted in the associated housing and connected to the associated terminals.

The interlocking member 163 is an elongated insulating member having a projection 193 that is engaged by the spring 167. The spring 167 biases the interlocking member 163 to the right as seen in FIG. 7 to the position wherein a cam surface 195 on the interlocking member 163 engages the lower fuse terminal of the removable fuse structure 95. The interlocking member 163 is provided with a hook part 197 at one end thereof for engaging and moving the latch member of the circuit breaker 157 when the interlocking member 163 is moved to the right.

The insulating housing 161 is formed with a slot 201 at the bottom thereof for receiving the interlocking member 163 when the housing 161 is moved into the mounted position. The housing 161 is molded to form a pair of keying parts 205 (FIG. 5) that t between Surfaces of the insulating housing of the circuit breaker 157 to provide support of the insulating housing 161 against lateral movement relative to the circuit breaker 157. During the assembly operation of the circuit interrupter 155, the interlocking member 163 is positioned in the cavity of the housing base of the circuit breaker and the circuit breaker cover is then riveted in position with the interlocking member 163 extending out through the end of the circuit breaker housing. Thereafter, the assembled fuse unit 159 is moved into position in the direction from front to back with the parts 205 (FIG. 5) moving down between the parallel surfaces of the insulating housing of the circuit breaker and with the interlocking member 163 (FIG. 7) passing up through the slot in the bottom of the insulating housing 161 of the fuse unit. Thereafter, the terminal screw 61 is screwed into position connecting the terminals 183, 59 to physically and electrically connect the circuit breaker 157 and fuse unit .159. As can be seen in FIG. 7 and as will be understood with reference to the previous embodiment, the circuit breaker contacts, the circuit breaker trip means, and the fuse structure of the fuse unit are connected in electrical series to operate upon the occurrence of overloads in the same manner as was described with reference to the rst embodiment. When the fuse of the fuse structure 95 is removed through an opening 208 in the front of the housing 161, the lower fuse terminal moves away from the cam surface 195 of the interlocking member 163 and the spring 167 biases the interlocking member 163 to the right whereupon the hook part 197 of the interlocking member 163 engages the latch member 51 to move the latch member 51 to the unlatching position to release the trip member of the circuit breaker whereupon the circuit breaker spring moves the trip member to the tripped position in the same manner as was hereinbefore described. Unless otherwise described, the circuit interrupter 155 operates in the same manner as was described with reference to the circuit interrupter 3.

While the fuse structure 95 is removed, the circuit breaker 157 cannot be reset and relatched for operation. When the fuse structure 95 is moved back into the mounted position seen in FIG. 7, the lower terminal of the fuse engages the cam surface i195 of the interlocking member 163 to cam the interlocking member 163 to the left to the inoperative position shown in FIG. 7. With the interlocking member 163 in the position shown in FIG. 7 the circuit breaker mechanism can be reset and relatched for a subsequent operation.

From the foregoing, it can be understood that there is provided by this invention an improved circuit interrupter comprising a circuit breaker and a fuse unit attached to the circuit breaker. The circuit breaker is a standard type of molded-case circuit breaker with thermal trip means for interrupting lesser overload currents with a time delay, and with electromagnetic trip means for interrupting higher overload currents instantaneously. The add-on fuse unit comprises a fuse structure for interrupting severe overloads to limit the current that will pass through the circuit breaker. Upon the occurrence of a severe overload, the fuse structure interrupts the overload letting through enough current to magnetically trip the breaker, but operating fast enough to interrupt the overload before the current reaches a value that would cause damage to the breaker parts. The combination comprises interlocking means for tripping the breaker when the fuse structure is removed from the front of the circuit interrupter and for maintaining the breaker in a tripped condition while the fuse structure is removed.

In one embodiment of the invention, the fuse unit comprises an insulating housing having the same dimensions as the circuit breaker and mounted in a side-by-side relationship with the circuit breaker. In the other embodiment of the invention, the add-on fuse unit is connected at the end of the circuit breaker.

In many distribution systems wherein this circuit interrupter may be used, available short circuit currents as high as 100,000 symmetrical RMS amperes are common. The circuit interrupter of this invention can be used in `this type of system to provide adequate and economical protection. The protective actions are coordinated so that overcurrents and low magnitude faults are cleared by thermal action, heavier overloads and normal short circuits are cleared by magnetic action, and abnormal short circuits, above an established Value, are cleared by the current limiting fuse unit to protect the circuit-breaker mechanism.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts may be made without departing from some of the essential features of the invention.

We claim as our invention:

1. A circuit interrupter comprising a circuit breaker anda fuse unit,

said circuit breaker comprising a first insulating housing having a iirst opening means at the front thereof, a circuit-breaker mechanism supported in said first insulating housing, said circuit-breaker mechanism comprising a pair of contacts, an operating handle extending from said iirst opening means and being manually operable to open and close said contacts, a latched releasable member releasable to effect automatic opening of said contacts, current responsive trip means in electrical series with said contacts and latching said releasable member, upon the occurrence of overload current conditions below a predetermined value said trip means operating automatically to a tripped position to release said releasable member,

said fuse unit comprising a second insulating housing having a second opening means at the front thereof, a fuse structure comprising an insulating fuse holder and a fuse supported on said insulating fuse holder, said fuse structure being supported on said second insulating housing with said insulating fuse holder at said second opening means to permit removal of said fuse structure from said second insulating housing through said second opening means,

each of said rst and second insulating housings comprising a front, a back, a pair of opposite ends and a pair of opposite sides, means securing said rst and second insulating housings together in a sideby-side relationship to form said circuit interrupter with said circuit interrupter comprising a front, a back, a pair of opposite ends and a pair of opposite sides,

said circuit breaker comprising a irst terminal at a iirst end of said circuit interrupter,

said fuse unit comprising a second terminal at the second end of said circuit interrupter,

conducting means providing a series circuit through said circuit interrupter from said lirst terminal through said contacts, said trip means and said fuse to said second terminal,

said fuse being constructed to blow upon the occurrence of overload current conditions above said predetermined value to interrupt the overload,

and interlocking means between said circuit breaker and said fuse unit operating automatically to eiTect release of said releasable member when said fuse structure is removed from said second insulating housing and to prevent closing of said circuit breaker while said fuse structure is removed from said second insulating housing.

2. A circuit interrupter according to claim 1, and said conducting means comprising plug-in terminal means for providing removable plug-in connection of said fuse structure in said series circuit.

3. A circuit interrupter according to claim 2, said interlocking means comprising an interlocking member er1- gaged by the fuse of said fuse structure and held in an inoperative position when said fuse structure comprising said fuse is in the mounted position thereof, spring means biasing said interlocking member toward a tripping position, upon removal of said fuse structure from said second insulating housing said interlocking member being released whereupon said spring means biases said interlocking member to said tripping position during which movement said interlocking member effects operation of said trip means to said tripped position.

4. A circuit interrupter according to claim 2, and each of said first and second insulating housings having substantially the same external dimensions.

5. A circuit interrupter according to claim 2, and said interlocking means comprising a spring-biased pivotally supported interlocking member held in an inoperative position when said fuse structure is in position on said second insulating housing and automatically released when said fuse structure is removed from said second insulating housing, upon removal of said fuse structure from said second insulating housing said spring biased pivotally supported interlocking member automatically moving to a tripping position to operate said trip means to the tripped position to effect release of said latched releasable member and to prevent relatching of said latched releasable member so long as said fuse structure is removed.

9 10 6. A circuit interrupter according to claim 3, said 3,284,598 ll/1966 George et al 337-194 interlocking member comprising a pivotally supported 3,280,280 10/1966 Gryctko 337-6 bell-crank lever comprising a rst leg cooperating with 3,202,788 8/ 1965 George 337-194 said fuse and a second leg cooperating with said circuit 3,118,991 1/1964 Scott 337 7 breaker trip means. Y.

BERNARD A. GILHEANY, Primary Examiner References Cited UNITED STATES PATENTS D. M. MORGAN, Assistant Examiner 3,354,277 11/1967 Stanback et al 337-8 U.S. Cl. X.R. 3,324,263 6/1967 onderko 337-6 10 337-8, 194 3,288,965 11/1966 Klein 337-70 

